Bump tensorflow to 2.6.0rc2 (#1491)
Bump tensorflow to 2.6.0rc2 (#1491)

This PR bumps tensorflow to 2.6.0rc2

Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>
tensorflow/io,tensorflow/io,tensorflow/io,tensorflow/io,tensorflow/io,tensorflow/io,tensorflow/io